New Swiss Study Confirms Sharply Lower Yields From Organic Crops

Dennis T. Avery

CHURCHVILLE, VA—Long-term field tests by a Swiss organic farming institute, as reported in Science on May 31, confirm that organic crops yield little more than half as much per acre as conventional farmers’ fields.

The Research Institute of Organic Agriculture in Frick, Switzerland said its organic yields were “only” 20 percent lower than the conventional yields in its comparison test plots, and used less energy while producing “healthier soils.”

However, the wheat yields in the Swiss organic tests averaged only 4 tons per hectare. The Swiss government says its national wheat average is 6 to 7 tons per hectare. The organic institute’s potatoes yielded only about 3 tons per hectare, compared to a Swiss national average that generally exceeds 4 tons per hectare.

Dr. Anthony Trevawas, a respected expert on European agriculture from the University of Edinburgh, noted that the Swiss organic institute has the level, high-quality soils typical of Swiss valleys, which should have supported much higher yields.

Dr. Trevawas said, “Organic farmers choose varieties carefully to minimize their severe pest problems, but such varieties usually have reduced yields. If the Swiss organic tests used the same varieties for their conventional plots—or simply didn’t select the top-yielding conventional varieties—this variety bias would make organic yields look better by comparison; but only for the purpose of the test. The poor yields achieved by the Swiss organic plots mean that organic farming in the real world could not feed our expected peak population without plowing down huge tracts of wildlife habitat.”

Dr. Trevawas said that, in Britain, both the recent Boarded Barns study and the Cooperative Wholesale Society report organic wheat yields about half as high as conventional ones.

He also noted that England’s Rothamsted experiment station has produced winter wheat continuously on some of the same test plots for 158 years. Some plots have received mineral-only fertilizer, some manure only. The two sets of plots have had identical yields, and currently produce about 9 tons per hectare—more than double the newly announced Swiss organic yields. This conflicts with the organic claim that mineral fertilizers reduce the long-term productivity of soils. Moreover, the heavy used of manure on Rothamsted’s organic plots have unfortunately caused the greatest nitrate pollution of waterways.

Dr. Paul Mader, the lead researcher in the Swiss organic test, said his organic test plots were home to a larger and more diverse community of soil organisms, with more microbes, more root-colonizing fungi and more earthworms than the conventional test plots. However, the Swiss test did not include conservation tillage, the newest and most rapidly spreading form of high-yield farming. In conservation tillage, the soil is not plowed. Instead,

herbicides are used to control weeds.

Dr. Mader said, “There are investigations that no-till [the most complete form of conservation tillage] in conventional [fields] shows better soil structure than plowed soils. Organic farmers still use the plow. However plowing is restricted to certain crops—in our experiment, three times in seven years.”

Conventional farmers are using conservation tillage on hundreds of millions of hectares in North America, South America, and Asia because it reduces soil erosion by up to 90 percent with no yield sacrifice.

Dr. Trevawas says no-till farming uses one-third as much fuel per ton of production as organic farming, because it eliminates the heavy fuel consumption in plowing. He noted that replacing the industrial nitrogen currently taken from the atmosphere (to comply with organic farming’s mandate for organic-only fertilizers) would require feeding another 7–8 billion cows and clearing billions of hectares of forest to grow more cattle feed.

Dr. Trevawas also warns that the potato disease problems in the Swiss tests may become chronic and contagious. “Two papers in recent scientific journals reported that organic farms can act as repositories of disease, and this paper would seem to confirm this possibility. Copper sulphate, which organic farmers have used up to now to deal with their potato disease problem, has recently been banned throughout the European Union because it is highly toxic to humans, and persistent.”

The organic farming community’s current focus on higher yields should be applauded. In the past they were pleased just to produce a harvest. But the world is already farming 37 percent of its land area, while the human population is still rising, and demanding better diets. The Swiss study leaves two critical questions: Can organic farmers triple their yields to help save wildlands? And how?

DENNIS T. AVERY is a senior fellow for Hudson Institute of Indianapolis and the Director of the Center for Global Food Issues. He was formerly a senior policy analyst for the U.S. Department of State. Readers may write him at Post Office Box 202, Churchville, VA 24421

This article was published by Knight Ridder Tribune

Dennis T. Avery is based in Churchville, Va., and is director of global food issues for the Hudson Institute of Indianapolis.

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